1951 FL Transmission rebuild

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51Hog
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1951 FL Transmission rebuild

#1

Post by 51Hog » Fri May 13, 2005 9:44 pm

I have a 51 FL Hand shift tranny. I bought a set of old Harley gears that are in great shape. I am using the 51 FL main shaft as it is in excellent shape. The Main shaft third gear that I bought is from a later model and does not use a bushing. It is machined to fit the main shaft and has the oil grooves cut into it.
The problem that I have is that the length of the gear (Parallel to the main shaft) is too long---By about 1/4 Inch. It does not mesh properly with the counter shaft third gear. Also, the snap ring that is supposed to hold main shaft third gear in place cannot be installed due to this extra length.
The question that I have is: Has anyone modified this gear to fit on their project? It looks like that if I put it on a lathe and cut this gear to size, it will both mesh where it is supposed to and it will let me put the snap ring in place.
Anyone have any thoughts on the subject?



57pan
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Re: Transmission rebuild 1951 FL

#2

Post by 57pan » Fri May 13, 2005 11:17 pm

I think it was 59 that they went to the longer 3rd gear, which was designed to be used with a redesigned 1st/2nd cluster gear. Rather than shorten the 3rd gear would it work to counter-bore the cluster gear so that you can leave 3rd gear as-is? It's my understanding that they changed the design because the 3rd gear was prone to wear making it harder to shift into 3rd.

Just a thought.

51Hog
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Re: Transmission rebuild 1951 FL

#3

Post by 51Hog » Fri May 13, 2005 11:22 pm

Sounds like a very good idea and possibly an option.
I need to measure to see how much beef will be left in the main shaft 1st 2nd cluster when it is cut out.

Cotten
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Re: Transmission rebuild 1951 FL

#4

Post by Cotten » Sat May 14, 2005 12:20 am

Bushed 3rd gears must be used with the matching cluster.
They were used with all tankshifts all the way through '65 (atleast).

Un-bushed 3rds (and the appropriate cluster) were spec'd for '52+ footshifts, although they can be fudged to work.

pthomas
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Re: Transmission rebuild 1951 FL

#5

Post by pthomas » Sat May 21, 2005 5:56 am

Yes, I have done what you are talking about. My trans would slip out of third gear on acceleration. I had some old harley gears from a shovelhead. Using a regular grinder I carefully ground down the gear so it fit nice. I think I ground out some of the face for oiling galleys? Now the tranny shifts sweet. Hard acceleration out of third gear is restored.

Cotten
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Re: Transmission rebuild 1951 FL

#6

Post by Cotten » Sat May 21, 2005 11:48 am

In case I was not clear, I meant that the gears should not be mismatched, however the footshift pair of gears could be used for handshift.
The Factory, however, found it best to keep the bronze bushing version in production for handshifts through '65, if not later.

I wasn't suggesting to grind the footshift third gear to mate the handshift cluster.

But if pthomas says it is possible, I'll take his word for it!

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